I think you misunderstood when you bought the Sony A900 into the equation, since you probably did not read what I wrote. I did not say a thing about the Sony A900. I was talking about the Nikon D3/D3s/D700.
Fine, the price difference between the D3x and D3s is 35%, whereas the price difference between the D3x and the A900 is 300%. I was addressing why there's such a discrepancy in price in the latter comparison, but the former comparison is probably mainly attributable to market forces rather than Sony unreasonably jacking up the price of the sensor.
Sony did not provoke this. Nikon did. By dropping Sony as a supplier for their D3 sensor and going outside. And then turning up with hat in hand at Sony's door, when they needed a high resolution FX sensor.
I suspect that the reasons for Nikon using Sony for the D3x and not for the D3/D700/D3s sensors has to do with sharing R&D. Probably Nikon is sharing R&D on the D3x sensor, but not on the D3/D700/D3s sensors.
Sony semi-conductor Kyushu (the sensor division of Sony) is probably as large or even larger than Nikon Corporation taken as a whole. Nikon will buy the sensors from Sony, whether they like it or not. There is no other supplier who can or will supply sensors to Nikon with the manufacturing critical mass that the Sony foundry has or the sheer R&D resources that Sony semiconductor has. Sony semiconductor not only supplier dSLR, video and p&s sensors but also makes several other types of sensors for a variety of industries, including the broadcast line and also higher-end video line which are a LOT more specialized and provides MUCH larger margins.
There are other manufacturers Nikon can turn to for their sensors. The fact that Nikon's number one selling FX sensor is now coming from a source other than Sony proves that Nikon has viable options. Also, the fact that the best low noise sensor on the market today was engineered completely in-house by Nikon and not Sony undermines your apparent assertion that Sony is driving the sensor R&D more than Nikon is.
Don't know what Thom is basing his conclusion on.
Like I said, Thom is privy to leaks and such, and he usually knows what sensors Nikon is considering in their next generation of DSLRs. Nikon uses prototypes in mules to test sensors, and Thom was aware of three different ones being tested, two of which now constitute Nikon's FX line-up, the third prototype might just be Nikon's next FX DSLR (there are some fairly strong rumors about an 18 MP sensor being used, and that too appears not to be tied to Sony).
I believe Nikon and Sony will continue their relationship in all spheres and even expand it even further. It is highly symbiotic, even if laypeople start making conclusions on specific actions with specific products.
It is not only notable that Nikon went elsewhere for the D3/D700/D3s sensors, but also that they didn't take a 14 MP sensor from Sony when they updated the D300 to D300s. Nikon is taking their sweet time on replying to Sony and Canon with a more modestly priced high MP DSLR, but perhaps in the next month or so (pre-PMA) Nikon may come out with something. If Nikon uses the D3x sensor again, then the explanation for Nikon's delay would be that they are simply pushing as many higher priced D3x sales as they can before undercutting it with a lower priced model; OTOH, if Nikon comes out with a different non-Sony sensor, then that would be one more piece of evidence that Nikon and Sony are diverging in sensor development.